Adsorptive properties of graphene oxide on vitamin B12 and their effect on the promotion of peripheral nerve regeneration.

OBJECTIVES: To observe whether Graphene oxide (GO) can absorb vitamin B12 (VB12) and Decellularized scaffold - acellular nerve allograft (ANA) modified GO-VB12 promote the repair of ischiadic nervus defects in a rat model. METHODS: The adsorption of GO on vitamin and the optimum adsorption conditions were investigated by single factor experiment. The adsorption properties of the material were observed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) to determine the success of adsorption on VB12. GO-VB12-ANA was prepared by vibration mixing method and bridged to injured ischiadic nervus. The nerve action potential, wet weight ratio of gastrocnemius muscle and the expression of GAP-43 were investigated by contrast test to detect its effect on nerve regeneration. RESULTS: The optimized adsorption conditions for GO on VB12 solution were listed as follows: adsorbent dosage was 6 mg, shaking time was 70 min, the pH value was 6, the optimum concentration of VB12 was 50 mg/L and the theoretical saturated adsorption capacity was 21.51 mg/g. The nerve action potential, wet weight ratio of gastrocnemius muscle and the expression of GAP-43 in nerve fiber of GO-VB12-ANA group were close to the normal values and significantly higher than those of ANA and rotation group. CONCLUSIONS: Based on the adsorption function of GO on VB12, GO-VB12-ANA can promote regeneration of injured ischiadic nervus, providing the experimental basis for the clinical application of nanomaterials.

The application of graphene oxidized combining with decellularized scaffold to repair of sciatic nerve injury in rats.

This paper combined the decellularized scaffold of sciatic nerve of rats with graphene oxidized (GO), studied and facilitated the regeneration of sciatic nerve of rats, and provided the basis for the clinical application of nanomaterials. GO was prepared through improving Hammer's Method. Fourier Infrared Spectrum was used to scan and detect the functional groups in GO of sample by using the pellet method, the microcosmic morphological appearance of GO was observed by using the scanning electron microscope. The GO/decellularized scaffold were prepared and operation bridging of injured sciatic nerve was conducted by using the oscillation mixing method. BL-420F Biofunctional Experiment System was used to detect nerve action potential and the maximum tension value of muscles, and the fiber structure of nerve was observed under H-7650 Transmission Electron Microscope (TEM). Scanning electron microscope observed that GO presented a folded and curly single-layer sheet structure. It was soluble in water through ultrasound, brownish, the Fourier Transform Infrared Spectrometer detected the absorption peaks of carbonyl, hydroxy and carboxy, proving that the surface of GO material had many functional groups containing oxygen. Decellularized scaffold combining with GO was applied to repair injury of sciatic nerve, the nerve action potential, maximum tension value of muscle, wet weight value of gastrocnemius, thickness of gastrocnemius, thickness of myelin sheath and diameter of axon of the decellularized scaffold combining with GO group were obviously higher than the decellularized scaffold group and the self-rotating group, approaching to the normal value. All the data were represented by means ± standard deviation ([Formula: see text]) and processed by adopting SPSS 11.0 software. Comparisons among groups were analyzed by variance, and the comparison of two means was detected by student t. The detection level adopted α = 0.05, when P < 0.05, it could be considered that there were significant differences. GO could combine with the biomaterial-decellularized scaffold to repair the injury of sciatic nerve and facilitate the regeneration of injured nerve. This provided new thoughts and theoretical & experimental bases for nanomaterials to be applied to clinic treatment of repair of nerve injury.

Induction of adipose-derived stem cells into Schwann-like cells and observation of Schwann-like cell proliferation.

The peripheral nervous system has the potential for full regeneration following injury and recovery, predominantly controlled by Schwann cells (SCs). Therefore, obtaining a sufficient number of SCs in a short duration is crucial. In the present study, rat adipose­derived stem cells (ADSCs) were isolated and cultured, following which characterization of the ADSCs was performed using flow cytometry. The results showed that the cells were positive for the CD29 and CD44 markers, and negative for the CD31, CD45, CD49 and CD106 markers. The multilineage differentiation potential of the ADSCs was assayed by determining the ability of the cells to differentiate into osteoblasts and adipocytes. Following this, the ADSCs were treated with a specific medium and differentiated into Schwann­like cells. Immunofluorescence, western blot and reverse transcription­quantitative polymerase chain reaction analyses showed that ~95% of the differentiated cells expressed glial fibrillary acidic protein, S100 and p75. In addition, the present study found that a substantial number of SCs can be produced in a short duration via the mitotic feature of Schwann­like cells. These data indicated that Schwann­like cells derived from ADSCs can undergo mitotic proliferation, which may be beneficial for the treatment of peripheral nerve injury in the future.

[Sequential expression of hypoxia-inducible factor 1alpha and its significance in secondary spinal cord injury].

OBJECTIVE: To investigate the expression pattern of hypoxia-inducible factor 1alpha (HIF-1alpha) in experimental secondary spinal cord injury (SSCI) in rats and its potential effects on SSCI. METHODS: A total of 66 SD rats (female or male) with weight (250 +/- 20) g were randomly divided into 3 groups: normal control group (group A, n = 6), pseudo injury group (group B, n = 6), and spinal cord injury (SCI) group (group C, n = 54). In group A, no treatment was given as normal control. In group B, only laminectomy was applied. In group C, laminectomy was applied and static compression model of SCI was built at T10 level. The expression of HIF-1alpha was measured with HE and immunohistochemical staining in groups A, B (1 hour after pseudo injury), and C (1, 3, 6, 12 hours and 1, 2, 3, 7, 14 days after SCI). Results All rats survived to the end of the experiment. HE staining showed that the spinal tissue of groups A and B were dense and the nucleus were round and big with light staining and clear nucleolus. The injured neuron at 1-12 hours after SCI of group C presented pyknosis and deep eosin staining. The swelling axon with bubbles and the disintegrated and disorganized medullary sheath in white matter appeared at 1-3 days after SCI. The hyperplasia of glial cells were obvious and gray matter cells were broken and apoptosis with cavities in injured spinal segment was observed at 7 and 14 days after SCI. Immunohistochemical staining showed that HIF-la was poorly expressed in group A and increased a little in group B. The positive expression in group C increased at 3 hours after SCI, which was found in spinal cord anterior horn neurons and a small amount of ganglion cells. It reached peak at 1 day, maintained at a high level during 1-3 days and then declined. At 14 days, it appeared only in a small amount of ganglion cells of white matter. There was no significant difference in the number of HIF-1alpha positive cells between groups A and B (t = 1.325, P = 0.137). The number of HIF-1alpha positive cells at each time point in group C was more than those in groups A and B (P < 0.05), and there were significant differences between all time points in group C (P < 0.05). CONCLUSION: The expression of HIF-1alpha increases after SCI, it is related to the ischemia hypoxia after SSCI, and the expression pattern was correlated with the injury time.